Offset duplicator



,Dec. 26, 1967 H. J. ZAHN ET AL OFFSET DUPLICATOR 8 Sheets-Sheet 1 Filed Oct. 25, 1963 Dec. 26, 1967 H. J-ZAHN ETAL OFFSET DUPLIGA'I'OR Filed 001;. 25, 1963 8 Sheets-Sheet 2 H wk 3 7 NH INVENTOR W W m 7 wk fl k M 1 W DR Dec. H J ZAH'QN ET AL OFFSET DUPLICATOR Filed Oct. .25, 1963 8 Sheets-Sheet Z INVENTOR Dec. 26, 1967 ZAHQ ET AL 3,359,893

OFFSET DUPLICATOR 8 Sheets-Sheet 4 Filed Oct. 25. 1963 INVENTOR wan/1 3W Dec. 26, 1967 H.J.ZAHN ETAL 8,359,893

OFFSET DUPLICATOR Filed Oct. 25, 1963 I 8 Sheets-Sheet 5 lln' llllllllllll Fig. 12

lllllllllul lllJlIll IN VENTOR Qfe ewn Dec. 26, '1967 H. J. ZAHN E AL 3,359,893

OFFSET DUPLICATOR Filed Oct. 25, 1963 8 Sheets-Sheet 6 x 2 LL.

o, '1 N N r 3 Filed Oct. 25,

8 Sheets-Sheet 7 INVENTOR 1W cum 2% United States Patent Z 9,999 28 Claims. (Cl. 191-91) This invention relates to an offset duplicator. On such a machine ink is transferred by means of an ink form roller to a master cylinder. Thereupon the ink is transferred from the master cylinder to a, rubber blanket cylinder and from there onto the paper or other material to be printed. A foil fixed on the master cylinder determines which parts of the paper have to be inked in printing. Now, if there were to produce additional copies f.i. of a written text differing only slightly from the original text till now one had to use a new foil. Say for instance, if letter headings and invoice forms have to be printed differing only in the word invoice, there had to be made hitherto two different foils, one carrying the word invoice and the other not carrying the word invoice.

It is an object of the present invention to use one foil only and to omit any part of the foil desirable in printing. In the above mentioned example one uses a foil with the word invoice and prints the sheets without or with the word invoice.

It is a further object of the invention to provide at least two ink form rollers having a cylindrical part which transfers ink to the said master cylinder; said cylindrical parts of all the ink form rollers having different lengths. It is a further object of the invention to provide an electrical control mechanism being actuated by one of said cylinders, said control mechanism pressing said ink form rollers with its cylindrical parts against the master cylinder or releasing them from said master cylinder. If a cylindrical part of one of the ink form rollers is in contact with the master cylinder, it colors a corresponding part of the foil and only this part is printed.

Using one of said ink form rollers for printing, in connection with the control mechanism the variabilities of omitting parts in printing are numerous. The possibility to omit a part in printing in the height of the sheets f.i. a line is immensely numerous, Whereas in the breadth f.i. in omitting a column, the number of possibilities depends on the number of the provided rollers of different length.

In order to secure also in the breadth a continuous variability it is a further object of the invention to make at least one of the rollers shiftable in an axial direction. By this development it is possible to get within the shifting zone any desirable column breadth in printing. For constructional reasons the shifting zone cannot be chosen unlimited. Therefore it is of advantage to choose this zone of a length that the difference of the length of the cylindrical parts of two different rollers will be bridged.

It is a further object of the invention to show a control mechanism actuating the ink form rollers very quickly, so that printing may be accelerated. The control mechanism may actuate the ink form rollers in a predetermined program. This means that the program cannot be changed. In a further object of the invention there are provided means to control several such programs. One may print according to one of said programs. For constructional reasons the number of such programs is limited.

Therefore it is a further object of the invention to provide a preliminary selection assembly. This assembly allows to print programs at choice.

Naturally it is possible to provide both the preliminary selection assembly and the means of the predetermined program. According to the invention a switch allows to change either to a predetermined program or to a preliminary program.

Further embodiments, modifications, and features of the offset duplicator of the present invention will be explained with reference to the accompanying drawings, wherein FIG. 1 is a perspective view of the offset duplicator of the invention.

FIG. 2 is the gearing to drive the control mechanism.

FIG. 3 is a gear for the preliminary selection of a program.

FIG. 4 is a sectional view along line IV-IV of the FIG. 3.

FIG. 5 is the switching diagram of the duplicator of FIG. 1.

FIG. 6 is a modification of the cam disk on FIG. 3.

FIG. 7 is a modification of the control mechanism of FIG. 4.

FIG. 8 is a further modification of the control mechanism of FIG. 4.

FIG. 9 is the side view of FIG. 8.

FIG. 10 is another modification of the ink form rollers of FIG. 1.

FIG. 11 is the switching diagram of a modified duplicator, working with a predetermined program and a preliminary program.

FIG. 12 is a gearing for printing several programs.

FIG. 13 is a switching table to effect printing after a chosen program.

FIG. 14 is an altered embodiment of the invention with respect to FIGURE 1.

FIG. 15 shows an altered embodiment of the control mechanism of FIG. 3 working with photocells according to FIG. 7.

FIG. 16 is a section through the device of FIG. 1 showing the cooperational organization of the device.

In FIG. 1 an ink form roller 2 transfers ink onto a master cylinder 1. The master cylinder 1 is turnable and transfers the inked zones onto a rubber blanket cylinder 3. Between the blanked cylinder 3 and an impression cylinger 4 the paper sheets to be printed pass. The ink form roller 2 receives its ink by an additional roller 6 to guartee a uniform print. The ink form roller 2 turns about a shaft 7. The ends of the shaft 7 are connected with the cores of two electromagnets 8 and 9. These electromagnets 8 and 9 press the ink form roller 2 towards the master cylinder 1 whenever they receive an electric impulse. As soon as the electromagnets 8 and 9 are disconnected from the voltage the springs 10 and 11 pull back the magnet cores and the ink form roller 2 is lifted from the master cylinder 1. In this position printing is interrupted because no ink will be transferred on to the master cylinder 1. The stroke of the magnets is adjustable by means of counter nuts 12 and 13. Furthermore the elasticity of the springs 10 and 11 is also adjustable by counter bearings 14 and 15. The counter bearings are fixed by counter nuts 16 and 17.

The magnets 8 and 9 are turnable on shafts 18 and 19. The shafts 18 and 19 are fixedly arranged in the machine. Shafts 18 and 19 lie parallel to the axis of the impression cylinder 4. The turnable arrangement of the magnets 8 and 9 effects that the ink form roller 2 will always roll on roller 6 when ink form roller 2 is pressed or lifted by the magnets 8 and 9.

Further ink form rollers 20, 21, and 22 are provided having cylindrical parts 23, 24, and 25 transferring the ink to the master cylinder. The parts 23, 24, and 25 have different lengths against another and with respect to roller 2. The rollers 20, 21, and 22 are acted by electromagnets 26, 27, 28, 29, 30, and 31 in the manner described in accordance with roller 2. The cylindrical parts 23, 24, and 25 of said rollers cause that in the axial direction only one certain zone of the master cylinder 1 is inked and consequently columns remain unprinted on the paper sheet. The well-timed pressing or lifting of one of the ink form rollers 2, 20, 21 or 22 causes that only certain zones of the foil in the height are printed so that it is possible to omit columns and lines in printing.

The magnets provided allow the pressing and lifting of the ink form rollers in dependence of the angle of rotation of the cylinder 3. This pressing and lifting may be controlled so that any desired line may be omitted in printing. The omission of columns, however, depends on the number of the provided cylinders of different length and therefore is discontinuous.

To reach in this case also a continuance the ink form rollers 2, 20, 21, and 22 may be displaceable in axial direction so far that they bridge the space between the cylindrical parts of two neighboured ink form rollers. Naturally it is possible that one of the rollers may be movable for a greater section in an axial direction (see FIG. 10). Here the ink form roller consists of a part 130 which transmits the ink to the master cylinder 1, and of a cylindrical part 131 of smaller diameter. Both parts 130 and 131 have the length of the master cylinder 1. The parts 130 and 131 are located in bearings 132 and 133. They are displaceable in the bearings 132 and 133 in the direction of the arrow 134. According to the range of displacement a certain breadth of the master cylinder 1 will be inked. In FIG. 10 lies the recess at the left hand side of part 130. Of course it could lie with the same result, too, on the right hand side of part 130.

Every one of the ink form rollers 2, 20, 21, 22 may be of the form as described in FIG. 10. Hereby it is possible too to ink a certain color on each roller to eifect a multicolor print.

The pressing and lifting of the ink form rollers 2, 20', 21, and 22 is effected by means of the electromagnets. These electromagnets are controlled by a control mechanism 57. The control mechanism 57 is driven by the blanket cylinder 3 by the help of a toothed wheel 58 and a toothed belt 32. The control mechanism 27 carries rotary buttons 33, 34, 35, 36, '37, 38, 39, and 40 which operate as follows: The rotary buttons 33 and 37 belong to the ink for-m roller 2; the buttons 34 and 38 to the roller 20; the buttons 35 and 39 to the roller 21; the buttons 36 and 40 to the roller 22. All the buttons allow by means of scales 41 till 48 to choose beforehand which lines are to be inked by the ink form rollers. The buttons 33 to 36 determine the time of pressing the ink form rollers 2, 20, 21, and 22 whereas the buttons 37 to 40 determine the release of the mentioned ink form rollers.

There is an additional press button 53 provided acting on a switch 53a (-FIG. This switch 53 acts on a relay 80 which acts the magnets 8 and 9. When actuated there is caused a permanent pressing of the ink form roller 2 against the roller 1. In the same manner button 54 effects a constant pressing of roller 20 against cylinder 1, button "55 of roller 21 and button 56 of roller 22.

Additional press buttons 49 to 52, however, cause on their actuation to change over to the preliminary choosing program, so that by means of the rotary buttons 33 till 40 the chosen lines become effective.

The toothed belt 32 drives a toothed wheel 60, as shown in FIG. 2. Wheel 60 is rigidly connected with a toothed wheel 61.

Into the toothed wheel 61 interlock further toothed wheels 62 till 65. Into the toothed wheel 65 interlocks a further wheel 67 and into wheel 67 two further wheels 67a and 300. Teeth of wheels 61 to 67a and 300 are not shown. Toothed wheel 64 is connected to a control disk 72 by means of shaft 70 (see FIG. 3). The control disk 72 has a groove 73 which opens short-termed a microswitch 74. The control disk 72 is connected with the rotary button 37 by means of a frictional ball hearing. The shaft 75 of the rotary button allows balls 76 to ride on semispherical shells 77 which stand in rigid connection with the control disk 72. The balls 76 are lodged in the extension 70a of the shaft 70. If the button 37 is turned then the rotation will be reduced and the control disk 72 correspondingly dislocated. The shaft 72, however, rests in its position. This dislocation serves for fixing the timing of pressing the corresponding ink form roller. If the shaft 70 is turned then this motion is forwarded directly to the control disk 72. This opens and shuts the switch 74 in dependence of its rotation angle, thus determining the pressing of the ink form roller 2 at the before fixed timing.

A corresponding steering disk 72a (see FIG. 5) is connected to the toothed wheel 63 and shuts short-termed a micro-switch 74a. The micro-switch 74 causes the pressing of the ink form roller 2 towards the master cylinder 1, whereas the switch 74a causes the lifting as described further down.

Each Wheel 61 to 67a of FIG. 2 is connected with a mechanism described in FIG. 3, each of said mechanisms effects the pressing or lifting of one of the ink form rollers, and each mechanism is adjustable by one of the buttons 33 to 40.

FIG. 5 shows the electrical circuit to control ink form roller 2. This circuit runs on direct current. The circuit is closed when the rotary button 53 is operated. Then the current flows from the plus pole via the switch 53a to a relay 80. When this relay is set under voltage then this relay shuts the switches 81 and 82. Now from the plus pole the current flows via the switch 81 into the windings of the magnets 8 and 9, so that these magnets pull the ink form roller 2 and press the same against the master cylin der 1. As per FIG. 5 the magnets =8 and 9 work under the influence of a quick exiter in the well known manner viz, by intercalation of a rheostate 84. Besides this a sparkle extinguisher is provided.

When the button 49 is to be pressed then the switches 85 and 86 are closed simultaneously. The control disk 72 shuts via the groove 73 short-termed the micro-switch 74. By this current is led to the relay via this switch so that the switches 81 and 82 are closed. The switch 74a actuated by the disk 72a is generally closed, so that over the switches 8 6, 74a and 82 the voltage on the relay 80 is permanent. Therefore flows the current permanently via the switch 81 to the windings of the magnets 8 and 9 and the ink form roller 2 is pressed against the master cylinder 1 during this time.

At the moment as the groove 73a of the disk 72a opens the switch 74a the relay 80 is without current and the switches '81 and 82 are opened. Consequently also the magnets 8 and 9 are without current and the springs 10 and 11 draw back the cores of the magnets so that the ink form roller 2 is lifted from the master cylinder 1.

An appropriate control is provided for each ink form roller 20, 21, and 22. The steering mechanism is actuated by the wheels 61 and 62, 65 and 66, 67 and 67a. These wheels turn disks according to the disks 72 and 72a of FIG. 5 acting in the same manner as in FIG. 5 on the magnets 26, 27 and 28, 29 and 30, 31. The circuit to control rollers 20, .21, 22 may lie parallel to the circuit described in FIG. 5 as indicated there by the broken lines 90 and 91.

FIGS. 11, 12, and 13 show an altered embodiment for controlling roller 2. In FIG. 12 a further wheel 300 is provided engaging wheel 67. Wheel 300 drives a shaft 301 rotatable in ball bearings 302 and 303. Fixedly arranged on the shaft 301 there are disks 203, 204, 205, and 206. Disks 203 to 208 are not adjustable, contrary to the disks of FIG. 5. They therefore only allow to print a rigid program. But disks 207 and 208 of FIG. 11 are adjustable like disk 72 in FIG. 3. These disks 203 to 208 act on switches 209 to 214. See FIG. 11. Switches 209 to 214 are arranged in a circuit in which a relay 202 operates a magnet pair 200 and 201, corresponding to FIG. 5. To these micro-switches 209 to 214 are installed beforehand additional switches 215 to 220 which are closed in couples by one of press buttons 221 to 223 each. See FIG. 13

5. too. Besides this a switch 53a is provided,'as per FIG. 5. The control disks 203 till 206 will be set rigidly for a predetermined program. As the magnets 200 and 201 f.i. instead of magnets 8 and 9 belong to an ink form roller ii. to ink form roller 2 there will be a permanent impression of the corresponding ink form roller 2 when closing the switch 53a. When pressing the buttons 221 or 222 the beforehand predetermined programs run off. When pressing the button 223 then the predetermined program is actuated which the operator can choose turning button 33 and 37.

An appropriate control may be installed for each ink form roller. These controls may be situated parallel to the described controls, and are indicated by broken circuits 190 and 191.

The control as shown in FIGS. 5 and 11 is not imperative. Naturally the switch disks as per FIG. 6 could also be constructed bipartite. In this case the part 100a carries a groove 101 and the part 102a a groove 103. Both these parts are turnable against each other so that the length of the groove is variable. If such a disk is provided, one micro-switch only is essential for the lifting and pressing of an ink form roller. In this case the controlled ink form roller is pressed as long as the micro-switch stands on the groove determined by the disks 100 and 102.

The micro-switches may naturally be substituted by photoelectric control assemblies, as shown as example in FIG. 7. From a light source 110 with an intermediary collimator 111 light will be sent through the grooves of the control disks 100 and 102, as per FIG. 6. A lens 112 collects the light upon a photocell 113. The produced voltage of the photocell 113 corresponds in its efliciency to a micro-switch.

Here, too, for pressing and lifting of the ink form rollers may be provided a separate photocell control, so that the switch diagram as per FIG. 5 is applicable.

FIG. 7 represents a rotary button 115 which guarantees the adjustment of the size of the zone for pressing and lifting by turning the disks 100 and 102 against each other.

As per FIGS. 8 and 9 the master cylinder 1 carries a code conveyor 120. Light rays coming from a light source 119 are directed by a condenser lens 121a to a diaphragm 122. The diaphragm 122 will be imaged by means of an objective 123 on the code conveyer 120. The image of the diaphragm 122 is again imaged on a photocell 125 by the help of an objective 124. The conveyer carries light absorbing marks. If such a mark coincides with the diaphragm picture then the photocell 125 will be covered with darkness and a control signal will be produced having the same effect as one of the microswitches, as in FIG. 5.

A respective mark could also be provided upon the paper sheets to be printed so that by this the control is released.

FIG. 14 shows an embodiment according to FIG. 1 but the impression cylinder 4 is movable in vertical direction by two electromagnets 400 and 401. In this embodiment sheets 5 only will be printed when the electromagnets 400 and 401 press the cylinder 4 against the cylinder 3. Electromagnets 400 and .401 are controlled by a mechanism as described in FIG. 3 with the aid of switching diagram of FIG. 5.

As further to be seen in FIG. 14 ink form roller 20 has two cylindricalparts 23 and 23' so that two columns may be printed on the sheets 5 at the same time if both cylindrical parts 23 and 23' transport ink.

FIGS. 7 and 15 show an altered embodiment of the invention. FIG. 7 is a perspective view of a detail of FIG. 15. The cylinder 3 drives with the belt 32 the gear 60. Connected with gear 60 is gear -61 which meshes with gear 62. Gear 62 is rigidly connected with the shaft 70. A lamp 110 gives light to a photocell 113 over lenses 111 and 112. Between the lenses 111 and 112 are arranged disks 100 and 102. These disks have recesses as shown in FIG. 7 so that in turning, photocell 113 alternatively gets light or not. The recesses of the disks and 102 are adjustable. For this purpose disk 102 carries teeth. With the teeth of disk 102 mesh teeth of a gear 410 connected to a button 115. If button is turned disk 102 turns against disk 100 so that the recesses of disks 100 and 102 shift against another. This shifting is provided to adjust the device. If the disks 100 and 102 turn, photocell 113 alternatively gets light. The current produced by photocell 113 flows over an amplifier 411 to a relay 80. Relay 80 shuts if no current is produced and opens if a current is produced. Relay 80 acts on a switch 81 as described in FIG. 5. Switch 81 acts on the electromagnets 8, 9. Relay 80 works with direct current by the aid of a rectifier 411.

FIG. 16 shows the cooperational organization of the device described in FIG. 1 or FIG. 14. Cylinder 3 drives over the belt 32 gear '60 which is rigidly connected to gear 61. Gear 61 meshes with gears 62 and 64. Gears 62 and 64 are rigidly connected with shafts 70 carrying the planet gearings 70a of FIG. 3. Planet gearing 70a carry the disks 72 acting on the switches 74.

What I claim is:

1. An offset duplicator comprising a master cylinder provided to carry a foil, a rubber blanket cylinder touching the said master cylinder, an impression cylinder, sheets to be printed passing between the said rubber blanket cylinder and the said impression cylinder, at least two ink form rollers having cylindrical parts transferring ink to the said master cylinder, said cylindrical parts of all the said ink form rollers having a difierent length, all the said ink form rollers having shafts and being turnable around said shafts, electromagnets engaging the ends of said shafts to press said ink form rollers against said master cylinder or to release said ink form rollers from said master cylinder, an electrical control mechanism actuated by one of the said cylinders, said control mechanism giving a voltage to the said electromagnets in dependance to the angle of rotation of one of said cylinders.

2. An otlset duplicator according to claim 1 characterized in that one of said ink form rollers has a length equalling the length of the master cylinder.

3. An offset duplicator according to claim 1 characterized in that the cylindrical parts of two of said ink form rollers have in sum the length of the master cylinder.

4. An ofiset duplicator according to claim 1 char-acterized in that the impression cylinder is liftable by the said control mechanism.

5. An offset duplicator according to claim 1 characterized in that at least one of said ink form rollers is movable in axial direction.

6. An offset duplicator comprising a master cylinder provided to carry a foil, a rubber blanket cylinder touching the said master cylinder, an impression cylinder, sheets to be printed passing between the said rubber blanket cylinder and the said impression cylinder, at least two ink form rollers having a cylindrical part transferring ink to the said master cylinder, the length of the cylindrical parts of all the said ink form rollers being dilferent, all the said ink form rollers having shafts and being turnable around said shafts, electromagnets engaging the ends of said shafts to press said ink form rollers against said master cylinder or to release said ink form rollers from said master cylinder, an electrical control mechanism actuated by one of the said cylinders, said control mechanism giving a voltage to the said electromagnets in dependance of the angle of rotation of said one of said cylinders, said control mechanism comprising an electrical circuit and means giving a signal to said circuit, said means actuated by one of said cylinders in dependance of the angle of rotation of said cylinder.

7. An offset duplicator comprising a master cylinder provided to carry a foil, a rubber blanket cylinder touching the said master cylinder, an impression cylinder, sheets to be printed passing between the said rubber blanket cylinder and the said impression cylinder, at least two ink form rollers having a cylindrical part transferring ink to the said master cylinder, said cylindrical parts of all the said ink form rollers having different lengths, all the said ink form rollers having shafts and being turnable around said shafts, electromagnets engaging the ends of said shafts to press said ink form rollers against said master cylinder, or to release said ink form rollers from said master cylinder, an electrical control mechanism actuated by one of the said cylinders, said control mechanism acting upon the said electromagnets, said control mechanism comprising mechanical elements, micro switches and relays, said elements being actuated by one of said cylinders, said elements acting on said micro switches, sa d switches acting on said relays, said relays acting on said electromagnets.

8. An offset duplicator according to claim 7 characterized in that said mechanical elements are fixedly arranged on the axis of one of said cylinders.

9. An offset duplicator according to claim 7 characterized in that a gear is provided driving said mechanical elements.

10. An offset duplicator according to claim 7 characterized in that said mechanical elements are cam disks actuating the micro switches.

11. An offset duplicator according to claim 7 characterized in that for each of said ink form rollers two disks having a recess on its circumference are provided each of the said disks giving a short impulse to a micro switch.

12. An offset duplicator according to claim 6 characterized in that there are provided a light source, optical elements forming a bundle of light rays, a disk being engaged to one of said cylinders said disk having a recess on its circumference, a photocell, said light rays falling through said recess onto said photocell.

13. An offset duplicator according to claim 7 characterized in that said mechanical elements are disks having a recess on its circumference, the ends of said recess being movable against one another.

14. An offset duplicator comprising a master cylinder provided to carry a foil, a rubber blanket cylinder touching the said master cylinder, an impression cylinder, sheets to be printed passing between the said rubber blanket cylinder and the said impression cylinder, at least two ink form rollers each having a cylindrical part transferring ink to the said master cylinder, the length of the cylindrical parts of all the said ink form rollers being different, all the said ink form rollers having shafts and being turnable around said shafts, electromagnets engaging the ends of said shafts to press said ink form rollers against said master cylinder or to release said ink form rollers from said master cylinder, an electrical control mechanism actuated by one of the said cylinders, said control mechanism giving a voltage to the said electromagnets in dependance of the angle of rotation of the one of the said cylinders, said control mechanism comprising a conveyer, optical elements, a photocell and a light source, light rays coming from said light source will be directed by said optical elements upon said conveyer and from there upon said photocell.

15. An offset duplicator according to claim 14 characterized in that the conveyer consists of marks printed upon the margin of the sheets to be printed.

16. An offset duplicator according to claim 6 characterized in that there are provided disks connected to one of said cylinders said disks having a recess on its circumference, said disks being adjustable to give a signal in dependence of a predetermined angle of oscillating of said cylinder.

17. An offset duplicator comprising a master cylinder provided to carry a foil, a rubber blanket cylinder touching the said master cylinder, an impression cylinder, sheets to be printed passing between the said rubber blanket cylinder and the said impression cylinder, at least two ink form rollers each of said rollers having a cylindrical part transferring ink to the said master cylinder, the length of the cylindrical parts of all the said ink form rollers being different, all the said ink form rollers having shafts and being turnable around said shafts, electromagnets engaging the ends of said shafts to press said ink form rollers against said master cylinder or to release said ink form rollers from said master cylinder, an electrical control mechanical actuated by one of the said cylinders, said control mechanism giving a voltage to the said electromagnets in dependance of the angle of rotation of the one of the said cylinders, said control mechanism comprising an electrical circuit and means giving a signal to said circuit, said means being actuated by one of said cylinders in dependance of the angle of rotation of said cylinder, there are provided further recessed disks connected to one of said cylinders, said disks being adjustable to give a signal in dependence of a predetermined angle of rotation of said cylinder comprising further a planet gearing having two shafts, balls arranged be tween said shafts so that in turning one of said shafts the other of said shafts turns with an altered speed, said one shaft carrying the said disks, said one shaft being connected with said cylinder and said other shaft carrying a handle.

18. An offset duplicator according to claim 17 characterized by a reduction gear between the said handle and the said disk.

19. An offset duplicator according to claim 1 characterized in that there is provided a control mechanism to print a predetermined program and a control mechanism to print a program at choice, a switch either putting into action the steering mechanism of the rigid program or of the selected program.

20. An offset duplicator according to claim 1 characterized in that the forces of the electromagnets acting upon the two ends of a shaft are adjustable.

21. An offset duplicator according to claim 1 characterized in that there are provided adjustable springs to adjust the force of the electromagnets.

22. An offset duplicator according to claim 1 characterized in that the electromagnets are turnable about a shaft lying parallel to the axis of the ink form rollers.

23. An offset duplicator according to claim 6 characterized in that the two electromagnets for each ink form roller are controlled by one common relay.

24. An offset duplicator according to claim 6 characterized by a switch acting upon the ink form roller having a cylindrical part equalling the length of the master cylinder to print the full program.

25. An offset duplicator according to claim 6 characterized in that there are provided two micro switches for each ink form roller lying in series, said micro switches being actuated by two steering disks one of them being generally closed and the other being generally opened.

26. An offset duplicator comprising a master cylinder provided to carry a foil, a rubber blanket cylinder touching the said master cylinder, an impression cylinder, sheets to be printed passing between the said rubber blanket cylinder and the said impression cylinder, at least two ink form rollers having cylindrical parts transferring ink to the said master cylinder, said cylindrical parts of all the said ink form rollers having a different length and the cylindrical part of one of the said ink form rollers having the length of the master cylinder, all the said ink form rollers having shafts and being turnable around said shafts, electromagnets engaging the ends of the said shafis to press said ink form rollers against said master cylinder or to release said ink form rollers from said master cylinder, an electrical control mechanism actuated by one of the said cylinders, said control mechanism giving a voltage to the said electromagnets in dependance to the angle of rotation of one of the said cylinders.

27. An offset duplicator comprising a master cylinder provided to carry a foil, a rubber blanket cylinder touchg the said ma ter cylinde an impression cylinder, sheets to be printed passing between the said rubber blanket cylinder and the said impression cylinder, at least three circumferentially spaced ink roller assemblies, each carrying an ink roll section, each of said sections being of different length, one of said sections being movable axially with respect to the master cylinder, electromagnets engaging the ends of the said shafts to press said ink form rollers against said master cylinder or to release said ink form rollers from said master cylinder, an electrical control mechanism actuated by one of the said cylinders, said control mechanism giving a voltage to the said electromagnets in dependance to the angle of rotation of one of the said cylinders.

28. An ofiset duplicator comprising a master cylinder provided to carry a foil, a rubber blanket cylinder touching the said master cylinder, an impression cylinder, sheets to be printed passing between the said rubber blanket cylinder and the said impression cylinder, at least two ink form rollers having cylindrical parts transferring ink to the said master cylinder, said cylindrical parts of all the said ink form rollers having a different length, all the said ink form rollers having shafts and being turnable around said shafts, at least one of said ink form rollers having two cylindrical parts spaced one from the other, electromagnets engaging the ends of the said shafts to press said ink form rollers against said master cylinder or to release said ink form rollers from said master cylinder, an electrical control mechanism actuated by one of the said cylinders, said control mechanism giving a voltage to the said electromagnets in dependance to the angle of rotation of one of the said cylinders.

References Cited UNITED STATES PATENTS 2,397,053 3/1946 Schneider 101137 2,893,310 7/1959 Johnson 101-182 2,931,294 4/ 1960 Ritzerfeld et a1 101132.5 2,967,475 1/1961 Ritzerfeld et al 10191 2,997,949 8/ 1961 Ritzerfeld et al 101-1325 3,083,637 4/1963 Ritzerfeld et al. 101132.5

EUGENE R. CAPOZIO, Primary Examiner. 

1. AN OFFSET DUPLICATOR COMPRISING A MASTER CYLINDER PROVIDED TO CARRY A FOIL, A RUBBER BLANKET CYLINDER TOUCHING THE SAID MASTER CYLINDER, AN IMPRESSION CYLINDER, SHEETS TO BE PRINTED PASSING BETWEEN THE SAID RUBBER BLANKET CYLINDER AND THE SAID IMPRESSION CYLINDER, AT LEAST TWO INK FORM ROLLERS HAVING CYLINDRICAL PARTS TRANSFERRING INK TO THE SAID MASTER CYLINDER, SAID CYLINDRICAL PARTS OF ALL THE SAID INK FORM ROLLERS HAVING A DIFFERENT LENGTH, ALL THE SAID INK FORM ROLLERS HAVING SHAFTS AND BEING TURNABLE AROUND SAID SHAFTS, ELECTROMAGNETS ENGAGING THE ENDS OF SAID SHAFTS TO PRESS SAID INK FORM ROLLERS AGAINST SAID MASTER CYLINDER OR TO RELEASE SAID INK FORM ROLLERS FROM SAID MASTER CYLINDER, AN ELECTRICAL CONTROL MECHANISM ACTUATED BY ONE OF THE SAID CYLINDERS, SAID CONTROL MECHANISM GIVING A VOLTAGE TO THE SAID ELECTROMAGNETS IN DEPENDANCE TO THE ANGLE OF ROTATION OF ONE OF SAID CYLINDERS. 